This invention relates to apparatus for forming a piecing end on a winding of yarn. More particularly, this invention relates to an apparatus for forming a piecing end of a winding of yarn by initially engaging the yarn to be wound with an auxiliary guide means.
In the manufacture of textiles, yarn is packaged by initially winding the yarn on spool cores. These spool cores have a main winding which is distributed over most of the spool, and a secondary winding distributed adjacent to one end of the spool which is used to splice windings on separate spools together. The secondary winding is called a piecing end, or perhaps, a piecing winding or a reserve winding. It is preferable that this piecing end not be secured to the spool coil with any type of closed loop.
The prior art discloses numerous approaches to the problem of forming piecing ends; however, these prior art approaches are generally rather complicated and require precise control and precise positioning of the yarn path. The general approach, when winding yarn with a zero twist, is to engage the yarn with a mobile auxiliary guide which controls the yarn during the time the yarn is wound to form the piecing end, and then by some means, transfers the yarn to a main yarn guide.
One prior art approach uses a simple hook which holds the yarn during the formation of the piecing end, and then allows the yarn to escape when the hook is retracted. This type of device is described, for example, in French Pat. No. 1,403,007 and U.S. Pat. No. 3,065,921. These guides, however, require a precise positioning of the path of the yarn, which is time consuming and requires some type of electrical or mechanical control means to retract the hook. This, of course, complicates the design and structure of the piecing end forming device. Furthermore, with this type of device, it is only possible to make piecing ends having coils which are joined or looped. Since joined or looped coils are difficult to splice, this approach leaves much to be desired.
Another type of auxiliary guide utilizes a ramp along which the yarn slides to form the piecing end on the winding coil. This type of guide usually slides or pivots to cause the yarn to slide along the ramp. Devices of this type are disclosed, for example, in French Pat. No. 1,479,764 and U.S. Pat. No. 3,166,262. These devices, however, require complex mechanical and pneumatic control systems which are difficult to regulate and require frequent adjustment. Consequently, these devices are both expensive and not necessarily reliable. As with the hook type devices, the ramp type devices require precise positioning of the path of the yarn.
The prior art also includes rotary auxiliary guides which are helical in shape and are formed by the coils of a coil spring or the threads of a helically threaded rod. These rotary guides may be mounted to idle on a shaft so as to be rotated by frictional forces between the yarn and the guides as the yarn is coiled, or on the other hand, may be driven positively by a drive means such as an electric motor. This type of guide is described, for example, in French Pat. No. 1,354,056 and French Pat. No. 1,439,305. As with the hook and ramp type auxiliary guides, these rotary guides require precise positioning of the yarn along a predetermined path in order to operate. In addition, since the pitch of the helices formed on these guides is fixed, it is impossible to vary the length of the piecing end without changing the rotary guide. An additional problem with this type of guide is that complicated driving and controlling systems are necessary when these guides are rotated positively.